The primary winding and the secondary winding of such a signal transmitter form a transformer which allows signal transmission between two galvanically decoupled circuits.
The disclosure herein relates in particular to signal transmitters for galvanically decoupled signal transmission which can be produced using the conventional methods from semiconductor technology on a silicon chip. These signal transmitters are normally formed by a plurality of planar coils located one above the other and do not have any ferromagnetic core to increase the inductive coupling between primary and secondary windings. These transformers are also referred to as “coreless transformers”.
It is hard to avoid parasitic capacitive coupling between the primary winding and the secondary winding of a signal transmitter. When a rapid change occurs in a voltage which is applied between the primary winding and the secondary winding —for example as a result of a reference-ground potential on the secondary side rising quickly with respect to a reference-ground potential on the primary side—then capacitive displacement currents can occur between the primary side and the secondary side. Such displacement currents induce voltages in line resistances, which are unavoidably present, in the primary and secondary windings, and in stray inductances, with these voltages being superimposed on the useful signals to be transmitted.